Metal lubricant



United States The present invention relates to the cold reduction of metals, as for example steel, and more particularly to improvements in the cold reduction of metals based on the utilization of novel lubricating compositions which have been found to possess a unique action upon the metal which is to be cold reduced.

The invention includes the lubricating compositions which are employed, the treated metal with the lubricating compositions coated thereon and also the process by which the metal is cold reduced and then heat treated to anneal the same without first removing the lubricating composition and without deleteriously affecting the metal by the failure to remove the said lubricating composition.

The present application is a continuation-in-part of my prior copending application Serial No. 475,835, filed December 16, 1954, now abandoned.

While a great variety of materials and various compositions are used as rolling oils in the cold reduction of metals and for protection against rusting, gouging, friction scratches, and also to provide good shape, gauge and surface finish, the compositions used for cold reductions heretofore have not been entirely satisfactory in a number of respects.

Of outstanding importance in the use of metal rolling lubricants is the fact that cold reduced metal is normally subjected to a heat treatment at elevated temperatures for the purpose of annealing the reduced metal. With the prior art processes, involving the use of palm oil, as the example of the standard and accepted lubricating composition, it was essential that the coating be removed prior to annealing, such as in the case of lithograph stock, otherwise staining and other types of surface blemishes would result.

In accordance with the present invention, the lubricating composition which is applied to the metal to be cold reduced consists essentially of sugar cane oil or an oleaginous composition containing sugar cane oil as the essential lubricating ingredient. It has been unexpectedly discovered that when sugar cane oil is employed as the essential lubricating ingredient, the metal which is so protected during the cold reducing procedure can be subsequently annealed without the necessity of removing the coating prior to annealing.

With the present invention, the sugar cane oil lubricant is left on after the metal has gone through the cold reduction steps. While not clearly and completely understood, it appears as though the lubricating compositions of the invention volatilize at substantially lower temperatures than the prior art products, permitting their removal at and during the annealing step, and this without leaving the tarnish and other deleterious surface effects which are produced whenever the prior art lubricating compositions were left on the metal during annealing of the cold reduced product. Briefly stated, the use of sugar cane oil as the essential lubricating ingredient in a metal treating procedure which involves cold reduction and annealing, permits the lubricated cold reduced metal to be annealed directly and without the need for an intervening cleaning step to free the metal of the lubricant coating. As a result of the present invention, the treatment of metal to cold reduce the same and then anneal the reduced product to obtain a satisfactory product having an unmarred clean surface is atent Q 3,031,749 Patented May 1, 1052 ice 2 greatly simplified by the elimination of an ordinarily necessary burdensome step, namely, the step of cleaning the metal to remove lubricating composition from the cold reduced product prior to annealing.

It is well known and shown, for example, in the patents to Montgomery 2,151,353 and 2,153,811 and the patent to Harris 2,258,552, to employ oil compositions including mineral oil compositions containing a fatty acid of an organic oil, and particularly palm oil, as metal coating compositions to prevent rust in the case of ferrous metals and as an aid to the cold drawing of metals. These prior art compositions produce staining or other deleterious results during annealing. Moreover, these prior art compositions do not emulsify well with water.

The basic inadequacy of the prior palm oil compositions mentioned hereinabove was recognized in the patent to Perry 2,590,451, who points out that palm oil has serious drawbacks in the field of rollinglubricants, in that it is difficult to remove from metal surfaces, thereby requiring the use of cleaners which greatly increases operating cost. It is also pointed out that palm oil, on annealing, stains and dirties the surface and exerts a detrimental effect When such metals are to be subsequently tinned, alloyed and the like. It is of interest to observe that Perry joins mineral lubricating oil with palm oil to indicate that both of these lead to staining of the metal surface upon annealing (at least insofar as spot testing of deoxidized black plate).

In accordance with the present invention, the sugar cane oil need not be highly refined. Instead there can be employed crude sugar cane wax (crude cane wax) which exerts a similar action in rolling as the sugar cane oil, or a mixture of sugar cane oil and crude cane wax. Any crude cane wax or sugar cane oil or mixture thereof can be used in accordance with the invention.

The sugar cane oil may be removed from the crude cane wax in any desired Way, but generally, as is known, it is derived from the wax by solvent extraction. See Journal of the American Oil Chemists Society, vol. 27, February 1950, pages 5760.

The following Table I gives an analysis range of the physical and chemical characteristics for typical sugar cane oils.

Table I Characteristic: Analysis Acid number 17-27 Saponification -160 Iodine value 100-115 Percent free fatty acid as oleic 5-14 Specific gravity 0.94-0.95

Refractive index 1.4700 Viscosity (cp. at F.) 45-70 solidification point F 30-50 Initial flash point P... 335-380 Percent Total acids 71.0 Water solublematerial 6.0 Unsaponifiable material 23.0

The total acids (71.0%) consist of approximately 82% free fatty acids of which about 50% are saturated and 50% unsaturated. Heptane insoluble acids are present to the extent of approximately 18%. The unsaponifiable material consists primarily of sterols in the amount of about 28% of the total unsaponifiables and. of hydrocar- 3 hens and alcohols to the extent of about 72% of the total unsaponifiables.

Crude cane wax is extracted from the filter press muds of a sugar cane crushing plant. Solvents such as acetone will separate the crude Wax into a hard wax and sugar cane oil. The waxes and oils which are separated from the bagasse during milling of the cane are removed from the crude sugar solution during clarification and appear in the filter press muds. The wax and oil can be extracted from the press mud by solvent extraction with solvents such as benzene, toluene, naphtha, heptane, etc.

Average constants for crude cane wax are presented in the following Table II.

Despite the variations which occur in the properties of crude cane wax and sugar cane oil, these materials are all usable and good results are obtainable irrespective of the specific crude cane wax or sugar cane oil which is selected.

It is not commercially practical to use the normally solid crude cane wax or the semi-solid sugar cane oil alone. In accordance with the invention, the sugar cane oil or the wax containing the oil is employed in admixture with a solvent carrier such as mineral oil, kerosene, etc., in order to provide stable mixtures of low pour point so that the resulting compatible mixtures may be easily employed at room temperature or at lower temperatures. Other solvent carriers such as hexalene glycol, propylene glycol, diethylene glycol, the glycol ethers and other organic solvents may be used. However, these other solvents are expensive and are not preferred.

An important feature of the invention is the fact that the desirable and unique attributes of sugar cane oil can be realized using a solvent carrier such as mineral oil. This is indeed surprising in view of the reported adverse results encountered by Perry in his tests. Nevertheless in the presence of the sugar cane oil, or the crude wax containing the oil, the presence of mineral oil does not cause staining of the metal surface when the cold reduced metal is annealed without removal of the sugar cane oil-mineral oil admixture. This surprising result which is achieved when a mineral oil carrier is used is indeed important when it is appreciated that the solvent carrier desirably occupies a major proportion of the lubricating composition which is actually applied to the metal surface.

When crude cane wax is mixed with mineral oil the physical character of the mixture varies with the proportion of crude cane wax in the mixture. When the crude cane wax content is 20% by weight of the mixture or less, the mixture is a liquid at room temperature and has a pour point of 20 F. or less. As the proportion of crude cane wax in the mixture increases, the pour point is increased and heating becomes necessary to apply the lubricant to the metal surface. A mixture of crude cane wax and mineral oil having a Weight ratio of 45:55 is a soft gel at room temperature. A 50:50 weight ratio of crude cane wax to mineral oil yields a harder gel at room temperature. The gels tend to be thixotropic.

The preferred mixtures, containing from 5% to 20% by weight of crude cane wax dissolved in a mineral oil medium, are easily applied at room temperature. For light gauge reduction of strip steel, e.g., a reduction in thickness of from 0.085" to 0.012", a preferred lubricating mixture contains 20 parts by weight of crude cane wax and 80 parts by Weight of mineral oil. For relatively heavy gauge reduction of strip steel, e.g., a reduction in thickness from 0.090" to 0.030", a mixture of 10 parts by weight of crude cane-wax and parts by weight of mineral oil is effective. The presence of 5% by weight of crude cane wax is sufiicient, when precoated on the metal after pickling, to prevent rust and to provide sulficient lubrication to permit heavy gauge reduction on a tandem reducing mill.

From the practical standpoint, 30% by weight of crude cane Wax represents the maximum proportion of wax in mineral oil which would be used for any cold reduction rolling. 10% to 20% by Weight of crude cane wax represents preferred proportions.

As previously indicated, the purposes of the invention may be accomplished using either the crude cane wax or the oil which is extractable therefrom. The crude cane wax is more effective but more expensive. The crude cane wax and the sugar cane oil may be used in admixture and this is preferred since the combination provides good performance at relatively low cost. The preferred ratio of crude cane wax to sugar cane oil, by weight, is 2:1. A particularly preferred admixture contains 10 parts by weight of crude cane Wax, 5 parts by weight of sugar cane oil and 85 parts by weight of paraffin oil.

' A preferred illustrative mineral oil is a neutral oil hav ing a viscosity of approximately 300 seconds (Saybalt) at F. and a specific gravity of 21 to 23 (degrees Baum) at 60 F.

The relative usable and preferred proportions of mineral oil are not significantly altered by the use of the sugar can oil in place of all or part of the crude cane wax.

The lubricant compositions of the invention may be used in a direct mill system in which the lubricant is not reused or in a recirculating mill system in which the lubricant is recovered and recycled. In the latter system, it is preferred to employ the crude cane wax and/ or oilsolvent carrier mixture in the form of an aqueous emulsion.

The wax and/oil-solvent carrier mixtures are selfemulsifiable although a small proportion, e.g., 1-5% by weight, of an emulsifying agent may be added beneficially. Any type of emulsifying agent, cationic, anionic or nonionic, may be employed. A preferred emulsifiable mixture contains 15 parts by weight of crude cane wax, 81 parts by weight of mineral oil and 4 parts by weight of sorbitol monooleate emulsifier. This mixture Will form a. relatively stable emulsion containing large volumes of Water, e.g., as much as about 98% by weight of water in the emulsion. The crude cane wax in the above illustrative emulsifiable mixture can be replaced in whole or in part by sugar cane oil.

An important attribute of an efiective lubricating composition is the load which the lubricant film can withstand before film failure. This is determined by the standard Four Ball Test which is used by industry to measure friction and load bearing capacity of a film before rupture.

Table III Lubricant Composition Load Failure, Cost. of lbs/in. Friction Palm oil, 10% F,F.A. (100%) 35, 870 0.029 Stearic Acid 53, 464 0. 0264 10% crude cane wax in parafiiu oil 72, 780 0.030 20% crude cane Wax in paratfin oil 143, 538 0. 045 30% crude cane wax in paratfin oil 149, 768 0.055 10% crude cane wax, 5% cane oil in paratfin oil 85, 197 0. 047 30% palm oil in paraffin oil 19, 047 0. 088

Coefficient of friction is approximately comparable to that of the standard palm oil mixture which was tested. The load bearing abilities of the compositions of the invention are remarkably superior. This property appears to account for the clean surface achieved in rolling the steel.

When used as a lubricating film during the cold rolling of strip steel, the lubricating compositions of the invention result in a brighter and cleaner surface, which is free of metallic pick-up and is far superior in this regard to conventional rolling lubricants comprising palm oil and the like. While the latter is a good rolling lubricant, it does have the undesirable property of producing a dirty surface.

While the reason for the unexpected utility of sugar cane oil for the lubrication of metal such as steel to facilitate the cold reduction of the metal is not clearly understood, it appears as through the particular hydrocarbons and alcohols and the ratios thereof which are present in the unsaponifiable fraction of the sugar cane oil impart to the lubricating composition unusual load bearing capacity which in turn prevents metal to metal contact and thus results in a clean steel surface. There is accordingly produced a unique action which leaves the metal surface brighter.

Use of the compositions of the present invention as a rolling lubricant during the cold rolling of steel demonstrates that good shape and flatness are achieved and that satisfactory reduction can be achieved using lower mill loads. This improvement will become evident from the data which is presented in the tables which follow in which comparative cold reductions were performed on a three stand tandem mill using mixtures of palm oil on the one hand and mixtures containing crude cane waxsugar cane oil mixtures. In the first comparison, the steel used was a low carbon steel strip having a width of 13 A" and a thickness of 0.097. In each run, the pressure applied was varied until the product produced had a thickness of 0.030. In run A, palm oil was cut to produce a 50% mixture with paraffin oil. In run B, 10 parts by weight of crude cane wax was mixed with 5 parts by weight of sugar cane oil and 85 parts by weight of paraflin oil. In each instance, the lubricating composition was applied to the strip steel by spraying the strip at the upcoiler (the device in which the strip is coiled before further use) after the strip had been pickled Both runs A and B produced strips of good shape and flatness. However, the strip produced in run A contained smudge and carbonaceous residue after annealing at 1340 F. for 60 hours in a reducing atmosphere. The strip produced in run B after the same annealing treatment was bright and free of smudge and carbonaceous residue.

In the tests which follow, a four stand tandem mill was used and the strip of steel reduced was a low carbon steel having a width of 28" and a thickness of 0.075". In each of runs A and B in which the compositions were the same as in runs A and B in Table IV, the strip steel was reduced to a finished gauge of 0.0142". However, these tests, the results of which are reported in Table V, were obtained using a supplementary mill lubricant. In run A, the supplementary lubricant was palm oil cut as a 50% mixture with parafiin oil and suspended in water in a concentration of 15% by weight. The suspension was continuously agitated and delivered by pump at a rate of 1.2 pounds per minute by spray at the exit side of the #2 and #3 stands. Each spray delivered the said 1.2 pounds per minute.

In run B, crude cane wax, sugar cane oil and paraflin oil in the 10:5:85 mixture specified hereinbefore was suspended as a 15% by weight mixture in water with continuous agitation and was delivered by pump at a rate of 6 1.2 pounds per minute per spray on the exit side of each of the #2. and #3 stands.

The results achieved are reported in the table which follows:

Table V Run A Run 200 AMP..- 200 AMP.

1,600 AMP 1 500 AMP 2,200 AMP- 2,050 AMP 2,200 AMP- 2 050 AMP Delivery Speedm- 1,360 ti/min-.- 1,360 ftJruin. Total load AMP 6,200 AMP. 5,800 AMP.

After annealing under the conditions specified in the tests shown in Table IV, it was found that the strip rolled in run A contained excess smudge and carbonaceous deposits. This strip steel was not satisfactory for use as lithograph stock. Normal mill practice in accordance with run A would have necessitated thorough cleaning of the strip after rolling and prior to annealing.

The strip rolled in run B was clean and bright and free of smudge and carbonaceous deposits. This strip was satisfactory for use as lithograph stock. The products of both runs A and B were rolled to good shape and flatness.

The water emulsions of the invention can be used to coat strip metal after pickling. A feature of the invention is that the water emulsions produced are easier to handle. When the lubricating composition is applied to heated metal from water emulsion, the water cools the metal surface and lowers the viscosity of the lubricant. As a result, an integral film is formed after the water evaporates. Gouges and friction scratches are minimized, and lubricant run off is avoided during the storage of the steel coils on the floor prior to tandem rolling. Such a precoating film also prevents friction scratches as the steel coil leaves the coil box and enters the tandem mill I claim:

1. A method of producing a cold worked and annealed product comprising applying to said metal product a surface coating comprising sugar cane oil as the essential lubricating ingredient dispersed in a hydrocarbon carrier, cold working said metal product and then annealing said metal product, such cold working and said annealing being performed while said surface coating remains upon the surface of said metal product.

2. A method of treating steel comprising coating said steel with a surface coating comprising sugar cane oil as the essential lubricating ingredient dispersed in a hydrocarbon carrier, cold working said metal having said surface coating thereupon and then annealing said cold worked steel without removing said surface coating from said steel to thereby obtain a cold reduced and annealed steel product having a clean surface.

3. A process which comprises applying to the surface of a metal a coating containing a material from the group consisting of sugar cane oil, sugar cane wax and mixtures thereof, said material being dispersed in a hydrocarbon carrier, and cold reducing the resultant metal.

4. A process which comprises applying to the surface of steel a coating containing a material from the group consisting of sugar cane oil, sugar cane wax and mixtures thereof, said material being dispersed in a hydrocarbon carrier, and cold reducing the resultant steel.

5. A method of producing a cold worked and annealed metal product which comprises applying to said metal product a surface coating comprising from 5% to 30% by weight of a material selected from the group consisting of sugar cane oil, crude cane wax and mixtures thereof dispersed in a hydrocarbon solvent, cold working said metal product and then annealing said metal product, said annealing being performed without removing said surface coating from said metal product.

6. A method of producing a cold worked and annealed References Cited in the file of this patent UNITED STATES PATENTS Dales et a1. Apr. 13, 1926 Craig Mar. 27, 1934 8 Montgomery Mar. 21, 1939 Montgomery Apr. 11, 1939 Harris Oct. 7, 1941 Perry Mar. 25, 1952 Kulakow Sept. 11,1956 Hlavacek Oct. 8, 1957 OTHER REFERENCES Association of Food and Drug Olficials of the United 10 States, Quarterly Bulletin, page 85 (1951).

Chemicals in Foods: A Report to the Association of Food and Drug Ofiicials on Current Developments by Lehman. Assoc. Food & Drug Ofiicials US, Quart. Bull. 15, page 85 (1951).

'UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,031,7 1) May 1, 1962 Nicholas M. Adams ied that error appears in the above numbered pat- It is hereby certif said Letters Patent should read as ant requiring correction and that the corrected below.

Column 4, line 25, for "(Saybalt)" read (Saybolt) column 5, line ll, for "through" read Lhougl column 6, line 40 after "annealed" insert metal Signed and sealed this 2nd lay of April 1963.,

SEAL) Attest:

ISTON G. JOHNSON DAVID L, LADD Attesting Officer Commissioner of Patents 

1. A METHOD OF PRODUCING A COLD WORKED AND ANNEALED PRODUCT COMPRISING APPLYING TO SAID METAL PRODUCT A SURFACE COATING COMPRISING SUGAR CANE OIL AS THE ESSENTIAL LUBRICATING INGREDIENT DISPERSED IN A HYDROCARBON CARRIER, COLD WORKING SAID METAL PRODUCT AND THEN ANNEALING SAID METAL PRODUCT, SUCH COLD WORKING AND SAID ANNEALING BEING PERFORMED WHILE SAID SURFACE COATING REMAINS UPON THE SURFACE OF SAID METAL PRODUCT. 